Removable device for relieving the compression stress on a cocked  firing-pin spring of a firearm

ABSTRACT

The device in this patent application will be called an “impact jag”. Similar in size to a bullet, the jag will be a short cylindrical device that can be threaded onto any and all firearms cleaning rods. The unthreaded end of the device will have a flat, blunt surface to be mated firmly against the breech face or bolt face of the firearm to completely cover the firing-pin hole when the cleaning rod is fully inserted into the firearm bore from the muzzle end. To relieve the energy of a stressed firing-pin spring, the firearm is dry fired on the unloaded chamber having the inserted impact jag in place. The released firing pin harmlessly transfers its energy to the impact jag and cleaning rod, or equivalent, thus relieving the stress on the firing-pin spring. After which, the cleaning rod and impact jag are withdrawn from the barrel.

BACKGROUND

All journals dedicated to firearms encourage letters or questions totheir gun editors. An often asked question is how long can a firearmremain cocked, or how long can the firing-pin spring of a firearm remainstressed before it is weakened or takes a set. The response always is,“We do not know”. Answers always are indefinite because there is no wayof knowing when or if a spring will be weakened. The concern is relativeto dangerous hangfires and misfires that result from weakened firing-pinsprings.

In centerfire cartridges a primer contains a chemical which when strucksolidly reacts explosively to ignite the propellant charge in thecartridge case. In centerfire rifles, pistols, and shotguns the primeris located in the center of the head of the cartridge case. To fire thecartridge of the firearm the primer is struck sharply by a firing pinwhen the trigger is pulled. The means by which the firing pin is driveninto the primer are many and varied. In one, the action of pulling thetrigger releases a hammer or striker driven by a strong spring to strikethe firing pin and drive it into the primer. In another, the action ofpulling the trigger disengages a sear which directly releases a cockedor stressed spring to drive a firing pin into the primer. The ultimatepurpose of the spring in this series of actions is directly orindirectly to drive the firing pin into the primer with sufficientenergy to cause the primer to ignite. Regardless of whatever name thesprings may be called in their multitude of various forms and actions,the springs will be referred to as firing-pin springs in thisapplication.

Firing-pin springs are either coil springs or flat springs, and weakenedsprings or springs that have taken a slight set will strike the primerof a cartridge with less energy. Whether the cartridge is factory-loadedor hand-loaded, to fire the cartridge requires a strong strike on theprimer, but if the spring does not have sufficient energy the cartridgewill hangfire or misfire. A hangfire is a dangerous situation where thecartridge will not fire for up to 30 seconds, or will not fire at all.The firearm must be pointed in a safe direction during that timeinterval. In either case, the firearm will be rendered useless until thefailed cartridge either fires after a delay or is removed unfired. Afailure for the primer to fire can be disastrous for the user, be theuser military, police, home or personal defender, target shooter,hunter, or dangerous-game hunter. Under stressful or careless conditionsa failure to fire when the trigger is pulled can become a life or deathsituation.

Is there a satisfactory solution? The energy of a stressed firing-pinspring can be relieved by dry-firing the firearm on an empty chamber,but this can snap off the tip of the firing pin or damage the firing-pinhole in the face of the breech or bolt of the firearm. This is notrecommended. Although the spring in some firearms can be relievedmanually, many cannot. No alternative relative to this problem is putforth in literature except to use snapcaps or dummy cartridges fordry-firing. But, snapcaps and dummy cartridges must be placed in thechamber of the firearm and must remain in the chamber indefinitelybecause they are not removable after use without reopening the firearmand automatically re-cocking the firing-pin spring. Therefore, eachfirearm must use a separate snapcap or dummy cartridge for each barrel.Thus, the need for a removable device is real.

DESCRIPTION OF THE DEVICE

Relative to firearms, “jags” are attachments that thread onto the end offirearms cleaning rods or cables for the purpose of scrubbing, cleaning,and oiling the bore of firearms barrels.

The removable device in the title of this patent application will becalled an “impact jag”. This jag will be a device to be used to relievethe stress on firing-pin springs. Similar in size to a bullet, the jagwill be a short cylindrical device that is threaded on one end to enableit to be attached to any and all firearms cleaning rods. FIG. 1 showsthe extraordinary simplicity of the proposed impact jag. The detail ofthe impact jag, pointed out by no. (1) in both end view and side view,shows that it has a cylindrical body with a blunt, smooth face (5). Theopposite end shown by no. (2) is threaded either male or female to allowattachment to a cleaning rod no. (4) of appropriate size and caliber.American cleaning rods usually are threaded female as seen at no. (2),whereas European cleaning rods usually are threaded male.Over-the-counter adapters to convert from one to the other are readilyavailable.

In use, the impact jag is attached to a cleaning rod (4) or equivalentand passed through the muzzle end of the bore of a barrel and insertedinto an unloaded chamber. The unthreaded end of the device at (5), ineach view, will have a flat, blunt, smooth surface which will be matedfirmly against the breech face or bolt face of a firearm to completelycover the firing-pin hole when the cleaning rod (4) is fully insertedinto the bore. A cocked firing-pin spring is under strong stress. Torelieve the energy of the stressed firing-pin spring, the firearm is dryfired to release the firing pin to strike the flat, smooth face (5) ofthe impact jag that has been placed over the firing-pin hole. Thereleased firing pin strikes impacts the impact jag and harmlesslytransfers its energy to the mass of the jag (1) and cleaning rod (4) orequivalent, thus relieving the stress on the firing-pin spring. Afterthe firing-pin spring has been relieved, the device is removed alongwith the cleaning rod when the cleaning rod is withdrawn from the barreland, therefore, leaving the chamber of the firearm empty, and safe andthe firing-pin spring relieved of stress until the next use of thefirearm whether it be one month, next game season, 10 years, or ageneration. And, the removed device is ready for the next barrel.

The device can be manufactured in diameters to fit specific calibers orin 2 or 3 appropriate diameters that, together, will fit all rifle orpistol bores, and in 2 or 3 different diameters to fit all shotgunbores. The device can be sized and threaded to allow attachment to anycleaning rod or cable commonly found in firearms cleaning kits.

Before using the impact jag, the same caution applies as before usingconventional cleaning-rods and jags, the chamber of the firearm must beinspected visually to verify that it is empty. The best time to use thedevice is after a firearm cleaning session.

1. The process of utilizing a cleaning rod, cable, or equivalent toplace an impact jag or other similar object against the breech or boltface of a firearm to cover the firing-pin hole.
 2. The process ofperforming claim 1, above, for the purpose of dry-firing the firearm todecompress the firing-pin spring and minimize any possibility that thespring can weaken or take a set over time.
 3. The process of relievingthe compression of a firing-pin spring with a device and then removingthe device, leaving the chamber of the firearm empty and safe.
 4. Themanufacture of any removable product similar to the described impact jagso that the firearm can be dry fired safely, thus relieving thefiring-pin spring without damage to the firing pin and without damage tothe firing-pin hole, thus leaving the chamber empty and safe.
 5. Themanufacture of any product similar to the described impact jag made ofmetal, plastic, rubber, or wood, or of any combination thereof whetherit be an integral part of a rod or cable, or an attachment to a cleaningrod or cable, so that the firearm can be dry fired, thus relieving thefiring-pin spring without damage to the firing pin and without damage tothe firing-pin hole, and then removing the product, thus leaving thechamber empty and safe.